When Frederick succeeded his father, he had Hohenstaufen Castle erected on the eponymous mountain in the Swabian Jura range, which became the ancestral seat of the dynasty.

When during the Investiture Controversy the Swabian duke Rudolf of Rheinfelden was elected anti-king to King Henry IV of Germany, Frederick remained a loyal supporter of the ruling Salian dynasty.

In turn Henry vested him with the Swabian ducal dignity in 1079 and also gave him the hand of his seven-year-old daughter Agnes of Waiblingen.

[4] In the last years of his reign, Frederick was able to expand the Hohenstaufen territories northwards, when he assumed the office of a Vogt (reeve) of Weissenburg Abbey and the Bishopric of Speyer in Rhenish Franconia.

[5] They had several sons and daughters, amongst whom were: After Frederick's death, Agnes secondly married the Babenberg margrave Leopold III of Austria in 1106.